1. Field of the Invention
The present invention relates to a CPP (current perpendicular to the plane) type magnetic detecting element that allows a sense current to flow in a direction perpendicular to the surface of a film, and more specifically, to a magnetic detecting element having a small magnetostriction constant λs and excellent soft magnetic properties.
2. Description of the Related Art
FIG. 5 is a partial cross-sectional view of a related art magnetic detecting element (spin valve type thin film element) H5 cut along a surface facing a recording medium.
Reference numeral 1 shown in FIG. 5 is a foundation layer formed of Ta, and a seed layer 2 formed of a bcc (body-centered cubic) structured metal such as Cr is formed on the foundation layer 1.
A multilayer film T, in which an antiferromagnetic layer 3, a fixed magnetic layer 4, a nonmagnetic material layer 5, a free magnetic layer 6, and a protective layer 7 are laminated sequentially, is formed on the seed layer 2.
The protective layer 7 is formed of Ta; the nonmagnetic material layer 5 is formed of Cu; the free magnetic layer 6 is formed of a ferromagnetic material such as CoFe or the like; the fixed magnetic layer 4 is formed of Heusler alloy such as Co2YZ alloy layer (Y is one or more elements selected from a group consisting of Mn, Fe, and Cr, and Z is one or more elements selected from a group consisting of Al, Ga, Si, Ge, Sn, In, Sb, Pb, and Zn); and the antiferromagnetic layer 3 is formed of an antiferromagnetic material such as PtMn or the like.
Electrode layers 10 and 10 are provided on upper side and lower side of the multilayer film T1, and a sense current, which is a direct current, flows in a direction perpendicular to the surface of the multilayer film.
An exchange-coupling magnetic field is generated at the interface between the antiferromagnetic layer 3 and the fixed magnetic layer 4, and the magnetization of the fixed magnetic layer 4 is fixed in a height direction (a Y direction in the drawings).
Hard bias layers 8 formed of a hard magnetic material such as CoPt or the like are formed on both sides of the free magnetic layer 6, and the top, bottom, and end of each hard bias layer 8 are insulated by an insulating layer 9. Magnetization of the free magnetic layer 6 is directed in a track width direction (an X direction in the drawing) by a longitudinal bias magnetic field from the hard bias layers 8.
If an external magnetic field is applied to the magnetic detecting element H5 shown in FIG. 5, the magnetization direction of the free magnetic layer changes relative to the magnetization direction of the fixed magnetic layer, and thus the resistance of the multilayer film changes. While a sense current with a fixed current is flowing, the external magnetic field is detected by detecting the change of the resistance as a voltage change.
The above magnetic detecting element is described in JP-A-2004-260149 (U.S. Pub. No. 2004/0165320 A1) In the magnetic detecting element described in JP-A-2004-260149, magnetization of the ferromagnetic layer is properly fixed in the height direction (the Y direction in the drawing) by using a Heusler alloy in the ferromagnetic layer functioning as the fixed magnetic layer 4 shown in FIG. 5 to obtain a magnetic detecting element having desirable properties.
In order to improve properties of a magnetic detecting element, it is very important to improve the soft magnetic properties by decreasing a magnetostriction constant λs. However, use of a Heusler alloy in the fixed layer 4 shown in FIG. 5 cannot improve the properties of the magnetic detecting element satisfactorily.